Nutrition: Per serving
Heat the oven to 160C/140C fan/gas 4. Put the onions cut-side up on a large baking tray, leaving space between each. Drizzle over the oil and dot over 35g of the butter. Season well. Scatter over half the oregano sprigs, then turn the onions over and add 100ml water to the tray.
Roast for 1 hr, then turn the onions over so they’re cut-side up and roast for 30 mins more until caramelised, soft and jammy – a knife should go through them easily. Add a splash of water and scrape up any caramelised bits. Leave to cool slightly.
Meanwhile, melt the remaining 50g butter in a small saucepan over a medium heat, stirring until it starts to brown and smell nutty. Pick the leaves off the remaining oregano sprigs and finely chop, then add to the saucepan along with the garlic, nigella seeds and some seasoning. Cook for 2-3 mins until fragrant. Remove from the heat and pour into a heatproof bowl or jug.
When you’re ready to serve, season the ricotta lightly with salt, then spread over a large serving platter. Arrange the onions on top, pouring over any roasting juices, then drizzle over the buttery sauce. Serve with crusty bread.
